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Clinton's campaign has turned to a host of celebrities, athletes and elected officials to be in early states when the candidate can't be there

The point of the surrogate operation, aides say, is to get the campaign's message in the news and allow people with credibility in certain communities to convey the campaign's message directly to voters

North Charleston, South Carolina (CNN)Rep. Bennie Thompson came armed with gifts -- and a message.

The congressman from the Mississippi delta sauntered into four barber shops on Sunday to stump for Hillary Clinton, offering prospective voters campaign signage, a photo of Clinton standing next to a younger Barack Obama in Unity, New Hampshire, and a warning for what happens if Clinton doesn't win the Democratic nomination.

The message was received loud and clear by the black barber and his customer in North Charleston who later told CNN that they plan to vote for Clinton. And it was a rebuke to Republicans that Clinton couldn't credibly deliver -- and would be criticized for saying.

With voters going to the polls in just weeks, Clinton's campaign has turned to surrogates like Thompson and a host of celebrities, athletes and elected officials to be in early states when the candidate can't be there. They stump for her in Iowa and New Hampshire, two critical early voting states, and attend fundraisers for her across the country.

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Secretary of Housing and Urban Development Julian Castro will fundraise for Clinton next week in Portland. New Jersey Sen. Cory Booker will headline six events for the former secretary of state in Iowa this weekend. And Demi Lovato, the singer and actress, will perform at a Clinton rally in Iowa on Thursday.

Although surrogates have become the norm in modern campaigning, the Clinton campaign has turned their operation into a key strength over Vermont Sen. Bernie Sanders, who leads Clinton be a sizable margin in New Hampshire and is catching up to her in Iowa.

The Clinton campaign has dispatched 34 different surrogates to Iowa, New Hampshire, South Carolina and Nevada as of this month, with many making multiple trips. These surrogates, according to a list provided by the Clinton campaign, include six U.S. senators, 14 members of Congress and three governors.

Members of the Congressional Black Caucus blanketed the Charleston area earlier this month around the fourth Democratic debate, stumping for Clinton in barber shops, beauty salons and church services. On Sunday, the day of the debate, 14 African-American politicians visited churches on behalf of the Clinton campaign.

The list also includes Bill Clinton and Chelsea Clinton, who have dramatically increased their roles in Clinton's campaign in the last month.

The point of the surrogate operation, aides say, is to get the campaign's message in the news and allow people with credibility in certain communities to convey the campaign's message directly to voters. The Clinton campaign keeps stats on how many people attend their surrogate events and track the amount of media attention the supporters receive.

Clinton's campaign has also invested heavily in their surrogate program, with five staffers dedicated to the project at their campaign headquarters in Brooklyn. Run by Adrienne Elrod, a longtime Clinton aide who work on her 2008 campaign, the team includes Michelle Kwan, the former Olympic athlete and herself a surrogate for Clinton at Asian America-Pacific Islander events.

What's more, the Clinton campaign has dispatched staffers to Iowa and New Hampshire to help coordinate the surrogate program on the ground, including traveling with the Clinton backers and planning their trips.

"Because (Clinton) can't be in multiple places at the same time, our surrogates are not only critical to delivering her message far and wide, but are also important advocates for articulating, in their own words, why they support Hillary becoming the next president of the United States," said Elrod, the director of strategic communications and surrogates.

Clinton's program is starkly larger than Sanders' surrogate operation, too.

Sanders' campaign has so far dispatched a handful of surrogates to points across the country, including rapper and activist Killer Mike, commentator and professor Cornel West, ice cream entrepreneur Ben Cohen, former Ohio State Sen. Nina Turner and climate activist Bill McKibben.

Sanders' wife, Jane, has also become a surrogate for the campaign. On Tuesday in Iowa, she broke away from her husband's bus tour and made three stops in Northwest Iowa.

Although Sanders' aides contend their surrogate operation is smaller because they are running against anti-establishment politics, they do acknowledge that Clinton has an advantage.

Back in South Carolina, Thompson left his fourth and final barber shop feeling confident about the work he had done for Clinton's campaign.

"One thing you've got to understand is there is a lot of risk," Thompson said in conversations with voters. "Unless you want (Donald) Trump to be president, you've got to vote."